Shielded electrical connector for spark plugs



April 24, 1951 N. J. Ln'ucHY 2,550,014

SHIELDED ELECTRICAL CONNECTOR FOR SPARK PLUGS Filed Jan. 15, 1944 ATTORNEYS Patented Apr. 24, 1951 SHIELDED ELECTRICAL CONNECTOR FOR SPARK PLUGS Noel J. Lituchy, Cedar Rapids, Iowa, assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application January 15, 1944, serial No. 518,387

6 Claims.

This invention relates to electrical apparatus, and more particularly to an electrical connection of the kind in which a flexible connector or cable is removably attached in a socket of a terminal member by a means which holds the connector lirmly and immovably in position within the socket when the device is assembled.

More specifically, the object of the invention is to produce an electrical connection of the type referred to which is so constructed that it is simple and inexpensive to make and one in which the connector can be readily inserted in the socket within which it is adapted to fit and which is provided with means by which the connector can be clamped in position in such socket without damaging the connector in any way and which will hold the connector in its socket in such a way that it can be disassembled if necessary without damaging the connector element.

The device is particularly adapted for use with a spark plug of an aviation engine. Prior to the development of this device, it was the custom to provide an outer sleeve of some resilient and insulating material which surrounded an inner insulating sleeve and had removably mounted thereon another short sleeve which, when the connector device was inserted in the socket in which it was adapted to be received, was clamped between two members to hold the connector in proper position relative to the socket and the plug. With such construction a retaining nut was used which was adapted to be screwed down on top of the plug and served to clamp the short sleeve in position and at the same time was effective to press the sleeve against theV inner sleeve to hold the connector in place. Difliculty was encountered in the use of this device because when the short outer sleeve was assembled over the inner sleeve and the retaining nut was screwed down to clamp the parts in assembled position as described. the outer sleeve was sometimes bent back on itself or otherwise distorted so that the connector would be wedged within the socket in which it fits and if it were desired, upon occasion, to remove the connector, it could not be pulled out of its receiving socket without damaging it to such an extent that it could not againbe used.

The present applicant discovered that instead of providing the two sleeves of insulating material, one of which is relatively tightly tted on the outer surface of the other, that such sleeves could be molded as a single piece and if this were done, that the difliculties above alluded to would b'e eliminated, that the connector would be held properly in place when the clamping `nut is tightened and yet if the nut were loosened from the plug, the whole connector could be removed from the socket in which it ts without any damage thereto.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a sectional view through the top of a spark plug and the connector element showing the parts in their assembledposition.

Fig. 2 is a side elevation of the sleeve of resilient insulating material, which, in accordance with applicants invention, is Vprovided in a single piece.

The upper portion of the spark plug is indicated in its entirety by the reference numeral 2. The plug has an outer metal sleeve 4 which surrounds an inner sleeve 6 of porcelain, or some other insulating material, At its upper end, the sleeve 4 is threaded and is adapted to be engaged by a clamping nut 8 which may be screwed onto the threaded portion of the top of sleeve 4 for they purpose of holding the electrical connector in proper position in engagement with the spark plug cavity in which such connector is received. spaced from the sleeve 6 is an inner sleeve 9 of porcelain or other ceramic insulating material, which extends upwardly from the lower part of the plug, not shown, and seated on the top of the sleeve 9 is a metallic contact piece lil which connects with a connecting element I2 that extends downwardly through the center of the plug. j

The connector element to which the present invention relates ts within the sleeve t and lncludes a sleeve I4 of porcelain, or other insulating material, which surrounds a reduced portion I5 of an outer sleeve of rubber, or some other resilient insulating material, which is indicated by the reference numeral I 8. This outer sleeve isA closed at its lower end as indicated at 2l), except for a small central aperture through which a wire 22 extends, the wire 22 being the contacting eley ment. This wire is spread out at its lower end and connects to a small metal sleeve 24, which is positioned within insulating sleeve I4. The wireis at the center of sleeve 24 which extends through an aperture formed at the center of an inwardly extending ange 26 which projects from the sleeve I 4 toward the axis thereof. The metal' element 24 is ilared at 28 to form a flange, which lies between the closed end 20 of the sleeve of insulating material I8 and the inwardly extending flange 25. Below the flange 26, the element 24 has another flange 3B, which is of lesser area than the inner diameter of sleeve I4 and is engaged by a helical spring 32, 'which is received between the metal contact piece I and the inwardly extending flange 26 of sleeve I4. This spring establishes contact between the contact piece I8, wire 22 and sleeve 24, when the connector is assembled in proper position.

The sleeve I8 is relatively short and surrounds an inner sleeve of insulatingmaterial 34 which4 is positioned adjacent the conductor element 22 and extends for the length of the conductor.

The sleeve I8 is providedwith a flange 36 extending outwardly from the periphery of the sleeve which is adapted to be` clamped between the beveled surface 38 which is formed at the lower end of a metal sleeve member 40. and a cooperating beveled surface 4I formed at the top of the sleeve 4. The member 40is brazed, or otherwiseV secured to one end of a metal tubular member 42 in the form of an elbow which surrounds the upper part of the sleeve I8 and is spaced therefrom as is shown in the drawings. Atits upper end, the sleeve 42 is brazed, or otherwise` secured to a flexible metallic sheath of woveny construction numbered 44 andA which surrounds the connector element. This woven sheath is connected to a metal sleeve 46- which is flanged at its inner end at-48 and the flange 48is engaged by a flange 5I)A formed in one end of the resilient sleeve I8.

The sleeve member 40, at its upper end, has a thin. wall 52, and this wall ts around the lower end `of the elbow member 42, which is slightly reduced in thicknessat 54, the portion 52 being brazed or otherwise secured to the reduced end ofthe sleeve 42, asindicated in the drawings.

The. nut 8 may be unscrewed from the'sleeve 'i 4 and when itis desired to connect the connect ing element with the spark plug, the sleeves I4 and I8, both of which are first assembled on the conductor member 22, are inserted in the space within the. insulating sleeve 6, as shown in Fig. l, and the nut 8 is then tightened on the upper threadedy portion of sleeve 4. Whenv this is done inwardly projectingiiange 56 of the nut engages an. outwardly projecting flange 58, which is formed on4 the lower end of the sleeve 4U to force the. sleeve 4I)l downwardly and clamp the projecting flange 36 between the surface 38 and the beveled surface 4I which is formed on a flange projecting inwardly from the metal sleeve 4, as previously set forth. When the nut is tightened, the conductor will be held rmly and immovably within its place within the socket in the spark plug and metallic contact made between the conductor element 32 andthe conductor piece I0 through the member 24 and the spring, so that the current is carried from the conductor 22 to the lpiece. I 0.

Referring to Fig. 2, as the device disclosed herein waspreviously constructed, that part of the sleeve I8 which is of larger diameter than themain portion of the sleeve and on which the flange 36. is formed, was made as a separate piece andk was received on theY outer surface of the mainpart of the sleeve I8. Whenthe insulating sleeve was made in this way with two parts and the nut 8 was tightened up to hold the conductor element in proper position within the plug, it was found that sometimes the short outer sleeve on which` the flange36 wasformed was distorted with. the-result that it would be jammed within the plug in such a way that if, for any reason, it was desired to disconnect the conductor from the plug, it could not be done without so injuring the insulating sleeve I8 and the part on which the iiange 36 is formed to such an extent that the conductor was no longer usable. The applicant found that by making the element I8 in one piece, so that the portion of the sleeve on which flange 36 is formed is integral with the entire sleeve member instead of a separate part, this difculty was avoided and the conductor could' be used andr disconnected from the spark plug as often as might be necessary without destroying it.

Whilefthe embodiment of the present invention as hereinL disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

l.. In combination with a spark plug having a metal tubular casing providing a socket withinthe casing, a metal conduit adapted to be connected tov said casing and surrounding a conductor cablea. part of which is received within said conduit and part of which extends beyond the end of said conductor to provide a terminal connectionwhich is adapted tobe received withinA said socket when said conduit and casing are connected together, said terminal connection comprising an insulated. electricalconductor element provided with acontact element at the end thereof and. having a sleeve of resilient insulating material comprisingA the outer insulating surface of said terminal connection and adapted toY projectv into said socket, said. sleeve being formed inone. single piece with a closed end provided with. a smallk orifice through which the conduit element extends and provided with a peripheral flange, adapted to be clamped between the. conduit and casing when said parts are connected together to hold the terminal connection in proper position,A said resilient sleeve having an enlarged portion adjacent the flange to form a shoulder on the outer surface of the sleeve, a short sleeve of non-resilient insulating material surrounding, the end of the resilient sleeve and held in position between the said shoulder and the contact element, and a sleeve of non-resilientv insulating materialV within the tubular element and definingthe socket in which the terminal connection is received.

2. Ink combination with a spark plug having a tubular metal casing providing a socket therein, a conductor cable adapted to extend into said socket and provided. with a contact member at the end of the cable which is received in. the socket,` av metal. conduit surrounding said conductor cable and adapted to be connected to the spark plug, an insulating sleeve within and contiguous to said metal housing,.a resilient. insulatingV sleeve comprisingV part of the conductor cable positioned within the metal conduit and extending into said socket when the conduit and spark plug are connected said last named. sleeve having parts of at least two different diameters, the part of greater diameter being positioned within and' of such a size as to engage the first mentionedv insulating sleeve, and being also providedr with an integral flange extending radially therefrom and clamping means for gripping the flange when the conduit is connected to the plug to hold theconductor cable in fixed position relative to the-plug.

3. Inl combination with aspark plug having a metal tubular casing providing a socket within the casing, a metal conduit adapted to be connected to said casing and surrounding a conductor cable, a part of which is received within said conduit and part of which extends beyond the end of said conduit to provide a terminal connection which is adapted to be received within said socket when said conduit and casing are connected together, said conductor cable including a conductor element, an insulating sleeve immediately surrounding said element and extending into said conduit and casing when said last named elements are connected, a second insulating sleeve immediately surrounding the rst sleeve and having an integral flange extending from its outer surface adapted to be clamped betwen the conduit and casing when such parts are connected together, said second sleeve being formed at the end which extends into said casing with a closed end integral with the sleeve and having a small orice formed in said closed end through which the conductor element extends.

4. In combination with a spark plug having a metal tubular casing providing a socket within the casing, a metal conduit adapted to be conf nected to said casing and surrounding a conductor cable, a part of which is received within said conduit and part of which extends beyond the end of said conduit to provide a terminal connection which is adapted to be received within said socket when said conduit and casing are connected together, said conductor cable including a conductor element, an insulating sleeve immediately surrounding said element and extending into said conduit and casing when said last named elements are connected, a second insulating sleeve immediately surrounding the rst sleeve and having an integral flange extending from its outer surface adapted to be clamped between the conduit and casing when such parts are connected together, said second sleeve being formed at the end which extends into said casing with a closed end integral with the sleeve and having a small orice formed in said closed end through which the conductor element extends, and a contact element supported on that portion of the conductor element which extends beyond the closed end of said second insulating sleeve.

5. In combination with a spark plug having a metal tubular casing providing a socket within the casing, a metal conduit adapted to be connected to said casing and surrounding a conductor cable, a part of which is received within said conduit and part of which extends beyond the end of said conduit to provide a terminal connection which is adapted to be received within said socket when said conduit and casing are connected together, said conductor cable including a conductor element, an insulating sleeve immediately surrounding said element and extending into said conduit andgcasing when said last named elements are connected, a second insulating sleeve immediately surrounding the rst sleeve and having an integral flange extending from its outer surface adapted to be clamped between the conduit and casing when such parts are connected together, said second sleeve being formed at the end which extends into said casing with a closed end integral with the sleeve and having a small orice formed in said closed end through which the conductor element extends, a contact element supported on that portion of the conductor element which extends beyond the closed end of said second insulating sleeve, and a retaining means at the end of the conductor element and adapted to hold said contact element in fixed position between the adjacent closed end of said second insulating sleeve and the retaining means.

6. In combination with a spark plug having a tubular metal casing providing a socket therein, a conductor cable adapted to extend into said socket and provided with a contact member at the end of the cable which is received in the socket, a metal conduit surrounding said conductor cable and adapted to be connected to the spark plug, an insulating sleeve within and contiguous to said metal casing, a resilient insulating sleeve comprising part of the conductor cable positioned within the metal conduit and extending into said socket when the conduit and spark plug are connected said last named sleeve having parts of at least two different diameters, the part of greater diameter being positioned within and of such a size as to engage the iirst mentioned insulating sleeve and being also provided with an integral flange extending radially therefrom, clamping means :for gripping the ilange when the conduit is connected to the plug to hold the conductor cable in xed position relative to the plug, a sleeve of non-resilient insulating material surrounding the smaller portion of the resilient sleeve and of substantially the same diameter as the larger part of said resilient sleeve and means for holding said non-resilient sleeve in position with one end thereof engaging a shoulder formed by the larger part of the resilient sleeve.

NOEL J. LITUCHY.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 965,684 Bierce July 26, 1910 1,912,115 Allen May 30, 1933 1,956,357 Leib Apr. 24, 1934 2,177,268 Stone Oct. 24, 1939 2,280,855 Rose Apr. 28, 1942 2,312,757 Frei Mar. 2, 1943 2,368,889 Setterblade Feb. 6, 1945 2,381,595 Hulsh Aug. 7, 1945 2,382,805 Mosthaf Aug. 14, 1945 2,399,390 Robertson Apr. 30, 1946 

